Shopping for the right bike can be a difficult process, especially if you don't know precisely what you want or need. Some people get caught up in the wrong places, looking at the simple aesthetics of the bike or flipping through the latest triathlon magazine at Borders to see what cool bike is underneath some professional triathlete in a crystal clear photo. While the bike's look should please you, it is, without question, the last idea on a fairly short list that should dictate your purchase.
First, consider your real budget. Bikes, especially the better brands, can skyrocket in price if you're not careful. If you are new to the sport, be careful not to buy the one with all the bells and whistles when you have yet to prove to yourself that you're going to stick with the triathlon. Nothing could be a worse investment than spending over two thousand dollars for a race or two worth of riding. Instead, set a clear budget that reflects your ability and goals, and never max out that allowance on just the bike itself. You will still need to outfit the bike with pedals, cycling shoes, a helmet, water bottle and cage, speedometer/odometer, etc. These extras can add up, so plan accordingly.
Next, think about the style you want. Most people select a basic road bike, and then upgrade it with features such as aerobars to make it work in a triathlon. The time trial bikes are for more experienced riders who know they will race on generally flat surfaces, and who can cycle in that aero position for an extended time. The majority of average to below average triathletes lack the strength to ride in that manner, thus a road bike is the better bet. Not to mention, the road bike works better for daily training and common hill work.
Finally, check with your local bike shop as to what frame will best suit your body style. Getting the right fit is more important than the brand name or color. If you have the bike custom fit with a computer generated program, you will leave the shop, whether it was a stock model or a personally constructed piece, with a bike that is prepared to maximize your ability.
Therefore, make fit, style, and budget huge priorities and don't get caught up in buying a bike that will look prettiest leaning against the garage. Buy with your brain and your body will thank you for it with each mile.